windows: Fix FS-related issues (#23369)

I've noticed an occasional error: `ignoring event C:\some\path\to\file
outside of root path \\?\C:\some\path`. This happens because UNC paths
always fail to match with non-UNC paths during operations like
`strip_prefix` or `starts_with`. To address this, I changed the types of
some key parameters to `SanitizedPath`. With this adjustment, FS events
are now correctly identified, and under the changes in this PR, the
`test_rescan_and_remote_updates` test also passes successfully on
Windows.

Release Notes:

- N/A

crates/util/src/paths.rs

@@ -1,4 +1,5 @@
 use std::cmp;
+use std::path::StripPrefixError;
 use std::sync::{Arc, OnceLock};
 use std::{
     ffi::OsStr,
@@ -113,6 +114,14 @@ impl SanitizedPath {
     pub fn to_string(&self) -> String {
         self.0.to_string_lossy().to_string()
     }
+
+    pub fn join(&self, path: &Self) -> Self {
+        self.0.join(&path.0).into()
+    }
+
+    pub fn strip_prefix(&self, base: &Self) -> Result<&Path, StripPrefixError> {
+        self.0.strip_prefix(base.as_path())
+    }
 }
 
 impl From<SanitizedPath> for Arc<Path> {
@@ -439,6 +448,14 @@ pub fn compare_paths(
     }
 }
 
+#[cfg(any(test, feature = "test-support"))]
+pub fn replace_path_separator(path: &str) -> String {
+    #[cfg(target_os = "windows")]
+    return path.replace("/", std::path::MAIN_SEPARATOR_STR);
+    #[cfg(not(target_os = "windows"))]
+    return path.to_string();
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;